scholarly journals Proximity proteomics in a marine diatom reveals a putative cell surface-to-chloroplast iron trafficking pathway

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jernej Turnšek ◽  
John K Brunson ◽  
Maria del Pilar Martinez Viedma ◽  
Thomas J Deerinck ◽  
Aleš Horák ◽  
...  
Keyword(s):  
Iron Acquisition ◽  
Nitrate Assimilation ◽  
Marine Diatom ◽  
Global Ocean ◽  
Cellular Respiration ◽  
Uptake System ◽  
Intracellular Iron ◽  
Critical Metal ◽  
Metal Cofactor ◽  
Biochemical Analyses

Iron is a biochemically critical metal cofactor in enzymes involved in photosynthesis, cellular respiration, nitrate assimilation, nitrogen fixation, and reactive oxygen species defense. Marine microeukaryotes have evolved a phytotransferrin-based iron uptake system to cope with iron scarcity, a major factor limiting primary productivity in the global ocean. Diatom phytotransferrin is endocytosed, however proteins downstream of this environmentally ubiquitous iron receptor are unknown. We applied engineered ascorbate peroxidase APEX2-based subcellular proteomics to catalog proximal proteins of phytotransferrin in the model marine diatom Phaeodactylum tricornutum. Proteins encoded by poorly characterized iron-sensitive genes were identified including three that are expressed from a chromosomal gene cluster. Two of them showed unambiguous colocalization with phytotransferrin adjacent to the chloroplast. Further phylogenetic, domain, and biochemical analyses suggest their involvement in intracellular iron processing. Proximity proteomics holds enormous potential to glean new insights into iron acquisition pathways and beyond in these evolutionarily, ecologically, and biotechnologically important microalgae.

scholarly journals Phytotransferrin endocytosis mediates a direct cell surface-to-chloroplast iron trafficking axis in marine diatoms

2019 ◽  
Author(s):  
Jernej Turnšek ◽  
John K. Brunson ◽  
Thomas J. Deerinck ◽  
Miroslav Oborník ◽  
Aleš Horák ◽  
...  
Keyword(s):  
Iron Acquisition ◽  
Nitrate Assimilation ◽  
Global Ocean ◽  
Uptake System ◽  
Intracellular Iron ◽  
Critical Metal ◽  
Metal Cofactor ◽  
Direct Cell ◽  
Biochemical Analyses ◽  
Iron Receptor

AbstractIron is a biochemically critical metal cofactor in enzymes involved in photosynthesis, respiration, nitrate assimilation, nitrogen fixation and reactive oxygen species defense. Marine microeukaryotes have evolved a phytotransferrin-based iron uptake system to cope with iron scarcity, a major factor limiting primary productivity in the global ocean. Diatom phytotransferrin is internalized via endocytosis, however proteins downstream of this environmentally ubiquitous iron receptor are unknown. We applied engineered ascorbate peroxidase APEX2-based subcellular proteomics to catalog proximal proteins of phytotransferrin in the model diatom Phaeodactylum tricornutum. Proteins encoded by poorly characterized iron-sensitive genes were identified including three that are expressed from a chromosomal gene cluster. Two of them showed unambiguous colocalization with phytotransferrin adjacent to the chloroplast. Further phylogenetic, domain, and biochemical analyses suggest their involvement in intracellular iron processing. Proximity proteomics holds enormous potential to glean new insights into iron acquisition pathways and beyond in these evolutionarily, ecologically and biotechnologically important microalgae.

scholarly journals Iron Acquisition in Mycobacterium avium subsp. paratuberculosis

2015 ◽  
Vol 198 (5) ◽  
pp. 857-866 ◽  
Author(s):  
Joyce Wang ◽  
Jalal Moolji ◽  
Alex Dufort ◽  
Alfredo Staffa ◽  
Pilar Domenech ◽  
...  
Keyword(s):  
Mycobacterium Avium ◽  
Iron Uptake ◽  
Genomic Island ◽  
Iron Acquisition ◽  
Laboratory Data ◽  
Uptake System ◽  
Intracellular Iron ◽  
Content Type ◽  
Iron Uptake System ◽  
Environmental Bacterium

ABSTRACTMycobacterium aviumsubsp.paratuberculosisis a host-adapted pathogen that evolved from the environmental bacteriumM. aviumsubsp.hominissuisthrough gene loss and gene acquisition. Growth ofM. aviumsubsp.paratuberculosisin the laboratory is enhanced by supplementation of the media with the iron-binding siderophore mycobactin J. Here we examined the production of mycobactins by related organisms and searched for an alternative iron uptake system inM. aviumsubsp.paratuberculosis. Through thin-layer chromatography and radiolabeled iron-uptake studies, we showed thatM. aviumsubsp.paratuberculosisis impaired for both mycobactin synthesis and iron acquisition. Consistent with these observations, we identified several mutations, including deletions, inM. aviumsubsp.paratuberculosisgenes coding for mycobactin synthesis. Using a transposon-mediated mutagenesis screen conditional on growth without myobactin, we identified a potential mycobactin-independent iron uptake system on aM. aviumsubsp.paratuberculosis-specific genomic island, LSPP15. We obtained a transposon (Tn) mutant with a disruption in the LSPP15 geneMAP3776cfor targeted study. The mutant manifests increased iron uptake as well as intracellular iron content, with genes downstream of the transposon insertion (MAP3775ctoMAP3772c[MAP3775-2c]) upregulated as the result of a polar effect. As an independent confirmation, we observed the same iron uptake phenotypes by overexpressingMAP3775-2cin wild-typeM. aviumsubsp.paratuberculosis. These data indicate that the horizontally acquired LSPP15 genes contribute to iron acquisition byM. aviumsubsp.paratuberculosis, potentially allowing the subsequent loss of siderophore production by this pathogen.IMPORTANCEMany microbes are able to scavenge iron from their surroundings by producing iron-chelating siderophores. One exception isMycobacterium aviumsubsp.paratuberculosis, a fastidious, slow-growing animal pathogen whose growth needs to be supported by exogenous mycobacterial siderophore (mycobactin) in the laboratory. Data presented here demonstrate that, compared to other closely relatedM. aviumsubspecies, mycobactin production and iron uptake are different inM. aviumsubsp.paratuberculosis, and these phenotypes may be caused by numerous deletions in its mycobactin biosynthesis pathway. Using a genomic approach, supplemented by targeted genetic and biochemical studies, we identified that LSPP15, a horizontally acquired genomic island, may encode an alternative iron uptake system. These findings shed light on the potential physiological consequence of horizontal gene transfer inM. aviumsubsp.paratuberculosisevolution.

scholarly journals Petrobactin, a siderophore produced by Alteromonas, mediates community iron acquisition in the global ocean

2021 ◽  
Author(s):  
Lauren E. Manck ◽  
Jiwoon Park ◽  
Benjamin J. Tully ◽  
Alfonso M. Poire ◽  
Randelle M. Bundy ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Iron Acquisition ◽  
Biogeochemical Cycling ◽  
Iron Bioavailability ◽  
Siderophore Production ◽  
Global Ocean ◽  
The North ◽  
The North Pacific ◽  
Alteromonas Macleodii

AbstractIt is now widely accepted that siderophores play a role in marine iron biogeochemical cycling. However, the mechanisms by which siderophores affect the availability of iron from specific sources and the resulting significance of these processes on iron biogeochemical cycling as a whole have remained largely untested. In this study, we develop a model system for testing the effects of siderophore production on iron bioavailability using the marine copiotroph Alteromonas macleodii ATCC 27126. Through the generation of the knockout cell line ΔasbB::kmr, which lacks siderophore biosynthetic capabilities, we demonstrate that the production of the siderophore petrobactin enables the acquisition of iron from mineral sources and weaker iron-ligand complexes. Notably, the utilization of lithogenic iron, such as that from atmospheric dust, indicates a significant role for siderophores in the incorporation of new iron into marine systems. We have also detected petrobactin, a photoreactive siderophore, directly from seawater in the mid-latitudes of the North Pacific and have identified the biosynthetic pathway for petrobactin in bacterial metagenome-assembled genomes widely distributed across the global ocean. Together, these results improve our mechanistic understanding of the role of siderophore production in iron biogeochemical cycling in the marine environment wherein iron speciation, bioavailability, and residence time can be directly influenced by microbial activities.

scholarly journals MavN is aLegionella pneumophilavacuole-associated protein required for efficient iron acquisition during intracellular growth

2015 ◽  
Vol 112 (37) ◽  
pp. E5208-E5217 ◽  
Author(s):  
Dervla T. Isaac ◽  
Rita K. Laguna ◽  
Nicole Valtz ◽  
Ralph R. Isberg
Keyword(s):  
Legionella Pneumophila ◽  
Transmembrane Protein ◽  
Iron Acquisition ◽  
Broth Culture ◽  
Growth Defect ◽  
Secretion Systems ◽  
Intracellular Growth ◽  
Iron Starvation ◽  
Macrophage Infection ◽  
Intracellular Iron

Iron is essential for the growth and virulence of most intravacuolar pathogens. The mechanisms by which microbes bypass host iron restriction to gain access to this metal across the host vacuolar membrane are poorly characterized. In this work, we identify a unique intracellular iron acquisition strategy used byLegionella pneumophila.The bacterial Icm/Dot (intracellular multiplication/defect in organelle trafficking) type IV secretion system targets the bacterial-derived MavN (more regions allowing vacuolar colocalization N) protein to the surface of theLegionella-containing vacuole where this putative transmembrane protein facilitates intravacuolar iron acquisition. TheΔmavNmutant exhibits a transcriptional iron-starvation signature before its growth is arrested during the very early stages of macrophage infection. This intracellular growth defect is rescued only by the addition of excess exogenous iron to the culture medium and not a variety of other metals. Consistent with MavN being a translocated substrate that plays an exclusive role during intracellular growth, the mutant shows no defect for growth in broth culture, even under severe iron-limiting conditions. Putative iron-binding residues within the MavN protein were identified, and point mutations in these residues resulted in defects specific for intracellular growth that are indistinguishable from the ΔmavNmutant. This model of a bacterial protein inserting into host membranes to mediate iron transport provides a paradigm for how intravacuolar pathogens can use virulence-associated secretion systems to manipulate and acquire host iron.

scholarly journals Neutrophil Gelatinase-Associated Lipocalin Expresses Antimicrobial Activity by Interfering with l-Norepinephrine-Mediated Bacterial Iron Acquisition

2010 ◽  
Vol 54 (4) ◽  
pp. 1580-1589 ◽  
Author(s):  
Marcus Miethke ◽  
Arne Skerra
Keyword(s):  
Iron Acquisition ◽  
Primary Source ◽  
Iron Complexes ◽  
Iron Complex ◽  
Immune Defense ◽  
Uptake System ◽  
Iron Chelate ◽  
Neutrophil Gelatinase Associated Lipocalin ◽  
Bacterial Uptake ◽  
Neutrophil Gelatinase

ABSTRACT l-norepinephrine (NE) is a neuroendocrine catecholamine that supports bacterial growth by mobilizing iron from a primary source such as holotransferrin to increase its bioavailability for cellular uptake. Iron complexes of NE resemble those of bacterial siderophores that are scavenged by human neutrophil gelatinase-associated lipocalin (NGAL) as part of the innate immune defense. Here, we show that NGAL binds iron-complexed NE, indicating physiological relevance for both bacterial and human iron metabolism. The fluorescence titration of purified recombinant NGAL with the FeIII·(NE)3 iron complex revealed high affinity for this ligand, with a K D of 50.6 nM. In contrast, the binding protein FeuA of Bacillus subtilis, which is involved in the bacterial uptake of triscatecholate iron complexes, has a K D for FeIII·(NE)3 of 1.6 μM, indicating that NGAL is an efficient competitor. Furthermore, NGAL was shown to inhibit the NE-mediated growth of both E. coli and B. subtilis strains that either are capable or incapable of producing their native siderophores enterobactin and bacillibactin, respectively. These experiments suggest that iron-complexed NE directly serves as an iron source for bacterial uptake systems, and that NGAL can function as an antagonist of this iron acquisition process. Interestingly, a functional FeuABC uptake system was shown to be necessary for NE-mediated growth stimulation as well as its NGAL-dependent inhibition. This study demonstrates for the first time that human NGAL not only neutralizes pathogen-derived virulence factors but also can effectively scavenge an iron-chelate complex abundant in the host.

scholarly journals Ferric Citrate Uptake is a Virulence Factor in Uropathogenic Escherichia coli

2021 ◽  
Author(s):  
Arwen E Frick-Cheng ◽  
Anna Sintsova ◽  
Sara N Smith ◽  
Ali Pirani ◽  
Evan S Snitkin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Iron Acquisition ◽  
Uropathogenic Escherichia Coli ◽  
Ferric Citrate ◽  
Uptake System ◽  
Lipocalin 2 ◽  
Compensatory Mechanisms ◽  
E Coli ◽  
Iron Source

More than half of women will experience a urinary tract infection (UTI) with uropathogenic Escherichia coli (UPEC) causing ~80% of uncomplicated cases. Iron acquisition systems are essential for uropathogenesis, and UPEC encode functionally redundant iron acquisition systems, underlining their importance. However, a recent UPEC clinical isolate, HM7 lacks this functional redundancy and instead encodes a sole siderophore, enterobactin. To determine if E. coli HM7 possesses unidentified iron acquisition systems, we performed RNA-sequencing under iron-limiting conditions and demonstrated that the ferric citrate uptake system (fecABCDE and fecIR) was highly upregulated. Importantly, there are high levels of citrate within urine, some of which is bound to iron, and the fec system is highly enriched in UPEC isolates compared to environmental or fecal strains. Therefore, we hypothesized that HM7 and other similar strains use the fec system to acquire iron in the host. Deletion of both enterobactin biosynthesis and ferric citrate uptake (ΔentB/ΔfecA) abrogates use of ferric citrate as an iron source and fecA provides an advantage in human urine in absence of enterobactin. However, in a UTI mouse model, fecA is a fitness factor independent of enterobactin production, likely due to the action of host Lipocalin-2 chelating ferrienterobactin. These findings indicate that ferric citrate uptake is used as an iron source when siderophore efficacy is limited, such as in the host during UTI. Defining these novel compensatory mechanisms and understanding the nutritional hierarchy of preferred iron sources within the urinary tract are important in the search for new approaches to combat UTI.

scholarly journals Dopamine Is a Siderophore-Like Iron Chelator That PromotesSalmonella entericaSerovar Typhimurium Virulence in Mice

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Stefanie Dichtl ◽  
Egon Demetz ◽  
David Haschka ◽  
Piotr Tymoszuk ◽  
Verena Petzer ◽  
...  
Keyword(s):  
Bacterial Growth ◽  
Iron Uptake ◽  
Iron Homeostasis ◽  
Iron Acquisition ◽  
Lipocalin 2 ◽  
Intracellular Iron ◽  
Content Type ◽  
Hepcidin Expression

ABSTRACTWe have recently shown that the catecholamine dopamine regulates cellular iron homeostasis in macrophages. As iron is an essential nutrient for microbes, and intracellular iron availability affects the growth of intracellular bacteria, we studied whether dopamine administration impacts the course ofSalmonellainfections. Dopamine was found to promote the growth ofSalmonellaboth in culture and within bone marrow-derived macrophages, which was dependent on increased bacterial iron acquisition. Dopamine administration to mice infected withSalmonella entericaserovar Typhimurium resulted in significantly increased bacterial burdens in liver and spleen, as well as reduced survival. The promotion of bacterial growth by dopamine was independent of the siderophore-binding host peptide lipocalin-2. Rather, dopamine enhancement of iron uptake requires both the histidine sensor kinase QseC and bacterial iron transporters, in particular SitABCD, and may also involve the increased expression of bacterial iron uptake genes. Deletion or pharmacological blockade of QseC reduced but did not abolish the growth-promoting effects of dopamine. Dopamine also modulated systemic iron homeostasis by increasing hepcidin expression and depleting macrophages of the iron exporter ferroportin, which enhanced intracellular bacterial growth.Salmonellalacking all central iron uptake pathways failed to benefit from dopamine treatment. These observations are potentially relevant to critically ill patients, in whom the pharmacological administration of catecholamines to improve circulatory performance may exacerbate the course of infection with siderophilic bacteria.IMPORTANCEHere we show that dopamine increases bacterial iron incorporation and promotesSalmonellaTyphimurium growth bothin vitroandin vivo. These observations suggest the potential hazards of pharmacological catecholamine administration in patients with bacterial sepsis but also suggest that the inhibition of bacterial iron acquisition might provide a useful approach to antimicrobial therapy.

scholarly journals Ferricrocin, a Siderophore Involved in Intra- and Transcellular Iron Distribution in Aspergillus fumigatus

2009 ◽  
Vol 75 (12) ◽  
pp. 4194-4196 ◽  
Author(s):  
Anja Wallner ◽  
Michael Blatzer ◽  
Markus Schrettl ◽  
Bettina Sarg ◽  
Herbert Lindner ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Iron Acquisition ◽  
Iron Starvation ◽  
Intracellular Iron ◽  
Iron Storage ◽  
Essential Metal ◽  
Iron Distribution ◽  
Iron Transporter

ABSTRACT Iron is an essential metal for virtually all organisms. Iron acquisition is well characterized for various organisms, whereas intracellular iron distribution is poorly understood. In contrast to bacteria, plants, and animals, most fungi lack ferritin-mediated iron storage but possess an intracellular siderophore shown to be involved in iron storage. Here we demonstrate that deficiency in the intracellular siderophore ferricrocin causes iron starvation in conidia of Aspergillus fumigatus, demonstrating that ferricrocin is also involved in intra- and transcellular iron distribution. Thus, ferricrocin represents the first intracellular iron transporter identified in any organism.

scholarly journals The 58-Kilodalton Major Virulence Factor of Francisella tularensis Is Required for Efficient Utilization of Iron

2009 ◽  
Vol 77 (10) ◽  
pp. 4429-4436 ◽  
Author(s):  
Helena Lindgren ◽  
Marie Honn ◽  
Igor Golovlev ◽  
Konstantin Kadzhaev ◽  
Wayne Conlan ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Iron Acquisition ◽  
Protein A ◽  
Intracellular Iron ◽  
Major Virulence Factor ◽  
Iron Pool ◽  
Isogenic Mutants ◽  
Schu S4 ◽  
Iron Concentrations

ABSTRACT We investigated the role of the 58-kDa FTT0918 protein in the iron metabolism of Francisella tularensis. The phenotypes of SCHU S4, a prototypic strain of F. tularensis subsp. tularensis, and the ΔFTT0918 and ΔfslA isogenic mutants were analyzed. The gene product missing in the ΔfslA mutant is responsible for synthesis of a siderophore. When grown in broth with various iron concentrations, the two deletion mutants generally reached lower maximal densities than SCHU S4. The ΔFTT0918 mutant, but not the ΔfslA mutant, upregulated the genes of the F. tularensis siderophore locus (fsl) operon even at high iron concentrations. A chrome azurol sulfonate plate assay confirmed siderophore production by all strains except the ΔfslA strain. In a cross-feeding experiment using medium devoid of free iron, SCHU S4 promoted growth of the ΔfslA strain but not of the ΔFTT0918 strain. The sensitivity of SCHU S4 and the ΔFTT0918 and ΔfslA strains to streptonigrin demonstrated that the ΔFTT0918 strain contained a smaller free intracellular iron pool and that the ΔfslA strain contained a larger one than SCHU S4. In contrast to the marked attenuation of the ΔFTT0918 strain, the ΔfslA strain was as virulent as SCHU S4 in a mouse model. Altogether, the data demonstrate that the FTT0918 protein is required for F. tularensis to utilize iron bound to siderophores and that it likely has a role also in siderophore-independent iron acquisition. We suggest that the FTT0918 protein be designated Fe utilization protein A, FupA.

Transferrin-mediated iron acquisition by pathogenic Neisseria

2002 ◽  
Vol 30 (4) ◽  
pp. 705-707 ◽  
Author(s):  
R. W. Evans ◽  
J. S. Oakhill
Keyword(s):  
Bacterial Cell ◽  
Iron Uptake ◽  
Binding Proteins ◽  
Current Knowledge ◽  
Iron Acquisition ◽  
Direct Interaction ◽  
Acquisition System ◽  
Uptake System ◽  
Short Account ◽  
Transferrin Binding Proteins

The pathogenic Neisseria have a siderophore-independent iron-uptake system reliant on a direct interaction between the bacterial cell and transferrin. In the meningococcus this uptake system is dependent on two surface-exposed transferrin-binding proteins. This short account will review our current knowledge of the transferrin-mediated iron-acquisition system of pathogenic Neisseria.

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